Flowise 3.1.3 Sandbox Escape via VM2 JavaScript Sandbox Bypass

Executive Summary

This is a sandbox escape vulnerability in Flowise versions before 3.1.3 that allows authenticated users to execute arbitrary code. It exploits a flaw in the vm2 JavaScript sandbox by bypassing path traversal checks using a fake String object with a match function. This enables loading and executing malicious JavaScript files stored outside the sandbox.

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Detection Guidance

Detecting this vulnerability requires checking the Flowise version in use. Run 'npm list flowise' or check the package.json file to verify if the installed version is below 3.1.3. Additionally, inspect server logs for unusual JavaScript file uploads or execution attempts, particularly via the File Loader or Custom Function Agent endpoints.

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Impact Analysis

An attacker could gain full control of the server by uploading a malicious JavaScript file and executing it outside the sandbox. This could lead to data theft, system compromise, or further network infiltration. The low attack complexity and lack of required privileges make exploitation easier.

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Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR and HIPAA requirements for data protection and confidentiality. A successful exploit may result in data breaches, leading to legal penalties, reputational damage, and loss of compliance certifications.

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Mitigation Strategies

Upgrade Flowise to version 3.1.3 or later immediately. Remove the moment library from dependencies if present. Replace the insecure vm2 sandbox with a more secure alternative like isolated-vm. Restrict access to authenticated users only and monitor for suspicious file uploads or code execution attempts.

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